Durability performance of one-part alkali-activated self-compacting concrete mixes under aggressive and elevated temperature conditions

Abstract

The growing demand for sustainable, high-performance materials in modern construction has driven the development of advanced concrete technologies. This study introduces one-part alkali-activated self-compacting concrete (OPASC) as a practical, safe, and user-friendly alternative to conventional Portland cement-based concretes. Selected mixes with compressive strengths exceeding 70 MPa were evaluated for durability under aggressive conditions, including extended exposure to 5 % sulfuric acid and 5 % magnesium sulfate up to 180 days. The thermal stability of these candidate mixes was also assessed by subjecting the mixes to sustained temperatures ranging from 200 °C to 800 °C. Chloride-ion resistance of these mixes was examined under bulk diffusion tests. Key durability indicators, including water absorption, permeable voids, and sorptivity, were quantified to evaluate matrix impermeability. The results revealed compressive strength losses of 25–32 % under acid exposure, 7–15 % under sulfate exposure, and 30–42 % under thermal exposure, with chloride diffusion coefficients ranging from 0.21 × 10⁻¹² to 0.32 × 10⁻¹² m²/s, indicating high resistance to ionic ingress. The mixes also exhibited low water absorption (3–4.5 %), lower soptivities (0.0024–0.0013 mm/s^1/2), and much reduced permeable voids (4.3–5.5 %), reflecting an impermeable, dense matrix. Microstructural analyses using SEM-EDS and XRD revealed that degradation under acid and sulfate conditions is primarily attributable to the decalcification of C/N-A-S-H gels, accompanied by the recrystallization of stable aluminosilicate phases. Finally, the environmental sustainability evaluation, which considered both embodied energy and carbon footprint, verified the superior environmental friendliness of OPASC mixes relative to conventional concrete. These findings confirm that OPASC exhibits superior chemical and thermal durability, reduced permeability, and enhanced resilience, thereby establishing it as a sustainable and practical solution for modern infrastructure applications.